Basalt with Iron Oxidation

Physical Properties

Hardness: 6 (Mohs scale), Color: Dark grey to black with reddish-brown oxidation, Luster: Dull to sub-metallic, Crystal structure: Aphanitic (fine-grained), Specific gravity: 2.8–3.0

Formation & Geological History

Formed from the rapid cooling of magnesium-rich and iron-rich lava at or very near the surface of a terrestrial planet or moon. The reddish tint indicates secondary weathering (oxidation) of iron-bearing minerals like olivine or pyroxene.

Uses & Applications

Commonly used in construction as aggregate, road base, and railroad ballast. In high-quality forms, used for stone sculpture or cast basalt liners.

Geological Facts

Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It is also found extensively on the Moon and Mars.

Field Identification & Locations

Identify in the field by its weight (dense), dark color, and fine-grained texture. Found globally in volcanic regions. Look for reddish-brown exterior 'crusts' (called a weathering rind) as seen in this specimen.

Identified on: 4/25/2026

Mode: Standard